Starter jaw meshing mechanism



Maly 3% M5@ R. M. HEIN-rz QEQJM'F STARTER JAW MESHING MECHANISM ATTORNEY May 30, 1950 R. M. HElNTz 2,509,757

STARTER JAW MESHING MECHANISM Original Filed Dec. 6, 1944 3 Sheets-Sheet 2 RALPH M HE/Nrz AT TORN E Y Maw v, i9@ R, M, HElN'f-Z llwfl STARTER JAW MESHING MECHANISM Original Filed Dec. 6, 1944 `.'5 SheetsSheet 5 INVENTOR. RALPH M, HEINTZ /l /l t() 4 ATTCR N EY with the jaw member. The spring 2l causes the jaw member to follow the nut 25 as the latter is extended on the shaft 3 until the jaw member becomes engaged and fully seated in its co-mating jaw member l2 on the engine. The outward travel of the nut 25 will then cease as soon as it loses its frictional engagement with the jaw member so that it is free to rotate with the shaft 3. A nut 33 on the bolt 35 serves both as an abutment for the spring 32 and as a stop to limit excessive outward movement of the parts inasmuch as it will ultimately come to bear against the end 34 of the shaft 3. The opposite end 35 of the shaft 3 constitutes a similar stop for the parts in their return movement so as to leave a clearance between the jaw member I2 and the starter housing when the jaw member is fully retracted.

The planetary gear ratio is such that the difference in rotational speeds between the sun gear and the planet carrier is much greater than the speed of sleeve it with respect to the housing,

- thereby providing a novel and rapid automatic means of traverse for extending the jaw member. When the starter motor begins to turn, the rotation of the shaft screws the cone nut 25 outwardly against the compression of spring 32 from its position in Figure l to approximately the position shown in Figure 2 wherein it is free to slip Within the jaw member i2 after the latter has engaged itself with the co-mating jaw I2' on the engine to be cranked.

It will be appreciated that as soon as slippage occurs between the cone nut 25 and the jaw member i2 the cone nut will merely rotate with the sun gear shaft 3 without extending itself further, clearance being provided between the shaft end 34 and the stop nut 33, as shown in Figure 2, when the jaw is seated.

When the engine fires while the starter is still cranking, the jaw member i2 will experience the usual ratchet action by the rapidly revolving engine jaw, causing the jaw i2 to reciprocate in and out on the cone nut against the compression of the jaw spring 2i. When the starter is switched off and stops revolving the jaw return spring 32 through the reaction of the bolt head 3| on the abutment washer 2l causes the cone nut to spin down to follow the inward motion of the jaw I2 each time the latter is cammed inwardly away from the cone nut by the revolving teeth on the engine jaw. In this manner the jaw I2 is finally returned clear of the engine jaw I2 where it is held by the action of the jaw return spring which y exerts a force considerably in excess of the jaw spring 2i.

Vibration of the parts tends to cause further slippage between the cone nut and the jaw I2 to finally return the jaw to its fully retracted position shown in Figure 1.

Figure 3 illustrates a modified construction in which the `jaw return spring is not required to oppose the main jaw spring, thereby having certain advantages over the arrangement of Figure l in that the relative strengths of the two Springs are not critical to satisfactory operation. This consideration is of particular importance where Y the two springs develop different characteristics In Figures 3 and 4 parts identical with Figures 1 and 2 are indicated by the same reference numerals. Thus it will be seen in Figures 3 and '4, as in the first embodiment, that the starter jaw I2 is splined for longitudinal movement in a driving sleeve III rotatable in a bearing 9, this sleeve constituting an integral part of a planet carrier I having planet gears G rotated by a sun gear 5 on a sun gear shaft 3 which is in turn driven by a ring gear 4. The starter jaw also has the previously described deep recess I9 in its tubular end I8 terminating in a spring seat 20. In this embodiment, however, the jaw spring 4U abuts a jaw spring retainer 4I carried by a cone nut 42 similar to the cone nut 25. As in the previous embodiment, the cone nut 42 has a conical end 43 having frictional engagement with a conical surface 44 on the jaw I2. A jaw return spring 45 is carried by a bolt 46 secured in the sun gear shaft, as shown, and having a head 4'I seated against the bottom wall I1 of the deep recess I6. A keyed nut 48 provides an end abutment for the spring 45 and also acts as a stop to limit the extension of the cone nut and jaw member. A spring retainer 5I) carried by an abutment washer 5I, or the like, within the cone nut, provides an abutment for the inner end of the jaw return spring 45. The spring 45 and the spring retainer 5B extend within a recess 52 in the end of the sun gear shaft.

The parts are normally at rest as shown in Figure 3 wherein both the main jaw spring and the jaw return spring are under only slight compression. When the starter begins to rotate, the cone nut 42 is screwed outwardly as in previous embodiment, by reason of the difference in rotational speeds between the sun gear shaft 3 and the planet carrier l. As the cone nut advances, it compresses the spring 45 and carries with it jaw spring retainer 4I, jaw spring 4Q, and the jaw I2 so that the latter is brought into driving engagement with the co-rnating engine jaw I2'. When the jaw I2 has engaged the jaw I2 so that it cannot extend any farther, the cone nut 42 will lose irictional engagement with the jaw I2 and will thereafter slip in the jaw without further travel, as in the previous embodiment. Such position of the parts is shown in Figure 4 wherein it will be seen that a slight clearance remains between the jaw return spring retainer 50 and the stop nut 48.

When the engine res while the starter is still cranking, the jaw I2 willbe rapidly cammed inwardly by the teeth on the rapidly revolving engine jaw I2 against the compression of jaw spring 40. Then, when the starter is switched oi and has ceased to rotate, the force exerted by jaw return spring 45 against the inner end of spring retainer 56 will spin the cone nut 42 down the steep spiral threads on the shaft3 until it again engages the jaw member. Successive impulses imparted to the jaw member l2 by the engine jaw I2 will in this manner thrust the starter jaw completely out of contact with the engine jaw, in which position it will be held by the cone nut. Under the constant return force exerted by the spring 45, vibration of the parts will tend to gradually retract the jaw I2 completely to its original position shown in Figure 3.

It will be noted that the above described retraction of the cone nut 42 in the embodiment sho-wn in Figures 3 and 4 is not opposed by the jaw spring 40. The action of the spring 45 is in no Way affected by the action of the spring 45. so

that the relative strengths of aging rates of the two springs is of no consequence to the satisfaci tory operation of the mechanism, Another advantage of this embodiment is that when the jaw is in returned, or rest, position botn springs are in their most relaxed conditions, increased spring stress occurring only during operation of the starter.

In both of the above described embodiments the extension of the starter jaw is entirely automatic in response to the initial rotation of the starter for an engine starting operation; and is effective to bring the starter jaw into deep seated engagement with the engine jaw so as to avoid damage to the jaw teeth resulting from tip engagement only, which has been a rather common occurrence in prior art jaw meshing mechanism. The invention includes all such variations in construction and arrangement of parts as fall Within the scope of the appended claim.

I claim:

In an engine starter having a planetary reduction gearing unit comprising a sun gear driving shaft and a driven planet carrier, an extendable jaw member splined in said planet carrier, a

conical friction surface in said jaw member, a. cone nut having a complementary conical friction surface, a jaw spring carried by said cone nut and acting against said jaw member to urge said surfaces into frictional engagement, a recess in said sun gear shaft, a bolt carried by said shaft in said recess, a tubular spring retainer carried by said cone nut and surrounding said bolt in said recess, and a jaw return spring around said bolt Within said spring retainer and bearing thereagainst to retract said cone nut and jaw member upon cessation of rotation thereof.

RALPH M. HEINTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,384,971 Rushmore Jul-y 19, 1921 1,901,997 Taylor Mar. 21, 1933 2,271,640 Heintz Feb. 3, 1942 2,303,637 I-Ieintz Dec. 1, 1942 

